(a) Technical Field
The present invention relates to a press of the pressure cell type. Presses of this kind are widely used for shaping complicated sheet metal parts, for example in the aircraft and automobile industries. One advantage is that they can be made with a very large working surface so as to enable the forming of large sheet metal parts in a single pressing operation.
(b) Prior Art
Presses of the kind to which this invention relates are disclosed, inter alia, in U.S. Pat. Nos. 3,875,778 (Hellgren), 3,938,361 (Claesson), 3,949,583 (Syvakari) in commonly owned U.S. patent application Ser. No. 692,716, filed Jan. 18, 1985 and now U.S. Pat. No. 4,573,335, in commonly owned U.S. patent application Ser. No. 823,326, filed Jan. 28, 1986, and in Pamphlet AQ 30-103 E published by ASEA AB of Vasteras, Sweden.
Heretofore, the trough- or tray-shaped carrying member, which is insertable into a cavity of the press, has been provided with loose sides, which during the pressing operation are pressed out against surrounding force-absorbing members in the press, usually elongated carrying members for the diaphragm, these carrying members resting against the sides of the press. These and other fill-out elements, which are designed to reduce the stresses on the diaphragm and a die cushion included therein or connected thereto, encroach upon the space and reduce the utilizable volume of the press space. The tool contained in the press space usually consists of a mold which is placed on the bottom of the trough or tray. On this mold is placed the sheet or workpiece to be formed. The sheet is pressed against the tool and is usually folded down against the sides thereof.